Traders work on the floor of the New York Stock Exchange on March 12. / Richard Drew, AP

by Kim Hjelmgaard and Adam Shell, USA TODAY

by Kim Hjelmgaard and Adam Shell, USA TODAY

NEW YORK - Hampered by economic and geopolitical risks abroad, stocks erased early gains and ended sharply lower Thursday as the Dow Jones industrial average dropped more than 200 points - its fourth-straight day of losses.

The drop came despite encouraging economic data in the U.S., showing rebounding retail sales in February and a steeper-than-expected drop in jobless claims.

But lingering concerns about a possible economic slowdown in China and building tensions in Ukraine continued to weigh on global markets.

The Dow finished down 231.19 points, off 1.4% to 16,108.89, and the Standard & Poor's 500 index dropped 1.2%, or 21.86, to 1,846.34. The Nasdaq composite index plunged 1.5%, or 62.91, to 4,260.42.

The Dow, which has come under pressure this week, is being weighed down by a variety of factors, ranging from a sense that stocks shot up too quickly after an early-year pullback to the recent worries about global growth and the conflict between Russia and Ukraine, says Quincy Krosby, a market strategist at Prudential Financial.

"The market has been acting tired," says Krosby. "When you add in the worries over China and Ukraine and the fact that the market has been trading near record highs, it is enough of an excuse to sell for investors that were looking for a reason for the market to pull back," says Krosby.

Retail sales rose a seasonally adjusted 0.3% in February, the Commerce Department reported before the market opened. That was better than expected and an improvement over January's 0.6% drop.

Weekly applications for U.S. unemployment benefits dropped 9,000 last week to a seasonally adjusted 315,000, a sign the job market is picking up after a winter slump.

Despite the positive economic data, investors remain concerned about the course of China's economy and the possibility of a broader fallout from the conflict in Ukraine, said Michael Levine, a portfolio manager at Oppenheimer Funds.

"Those two things are tempering enthusiasm right now," he said.

President Obama said Thursday that if Russia continues an aggressive path in Ukraine, the United States and other countries will be "forced to apply costs" to Moscow. Obama made his remarks after meeting with Ukraine's new prime minister, Arseniy Yatsenyuk, at the White House.

The yield on the 10-year Treasury note tumbled to 2.65% from 2.73% late Wednesday as bond prices rose. The yield affects rates on mortgages and other consumer loans.

In corporate news, Plug Power reported revenue jumped to $8 million as the alternative energy company lined up some big clients. The news caused its shares to vault 18% to $8. The stock has been rising in recent weeks.

Oil prices rose slightly as a barrel of benchmark crude for April delivery was up 21 cents to $98.12 in electronic trading on the New York Mercantile Exchange. The contract fell $2.04, or 2%, to close at $97.99 on Wednesday.

U.S. stocks closed mixed on Wednesday, as the Dow fell 11.17 points, or 0.1% to close at 16,340.08. 16,108.89. The Dow has now fallen for three consecutive days. The S&P 500 index was basically flat, rising 0.57 to 1,868.20 and the Nasdaq composite index rose 16.14 points, or 0.4% at 4,323.33. The Nasdaq broke its four-day losing streak.